by Judith Curry
Well, if you judge ‘sides’ by what climate scientists have to say about the science, it is getting difficult to tell.
Kevin Trenberth was interviewed on NPR last nite, the ‘balance’ for my interview. I found several statements in this story to be interesting in terms of trying to delineate my ‘skeptical’ perspective from Trenberth’s ‘consensus’ perspective.
The ‘pause’
From Trenberth’s NPR interview:
So will the oceans come to our rescue?
“That’s a good question, and the answer is maybe partly yes, but maybe partly no,” he says.
The oceans can at times soak up a lot of heat. Some goes into the deep oceans where it can stay for centuries. But heat absorbed closer to the surface can easily flow back into the air. That happened in 1998, which made it one of the hottest years on record.
Trenberth says since then, the ocean has mostly been back in one of its soaking-up modes.
“They probably can’t go on much for much longer than maybe 20 years, and what happens at the end of these hiatus periods, is suddenly there’s a big jump [in temperature] up to a whole new level and you never go back to that previous level again,” he says.
20 years!!! From his statement it is not quite clear what the starting date is for the 20 years: whether it is now and 20 MORE years, or whether it started in 1998 with 20 years presumably taking us to 2018. In any event, this is definitely not what the consensus said in the 2007 AR4 report, and based upon what I have seen of the AR5, this is not what I would expect the AR5 to say.
A reminder of what I said on this topic in my Congressional testimony:
When considering possible physical reasons for the plateau since 1998, it is instructive to consider the previous mid-century plateau in global average surface temperature. The IPCC AR4 explained this previous plateau in the following way: “the cooling effects of sulphate aerosols may account for some of the lack of observational warming between 1950 and 1970, despite increasing greenhouse gas concentrations.”
With regards to multi-decadal natural internal variability, the IPCC considers this issue primarily in context of detection of an anthropogenic warming signal above the background ‘noise’ of natural variability. The IPCC’s attribution of the late 20th century warming has focused on external radiative forcing, and no explicit estimate of the contribution of natural internal variability to the warming was made. A recent paper by Tung and Zhou suggests that the anthropogenic global warming trends might have been overestimated by a factor of two in the second half of the 20th century. They argue that a natural multidecadal oscillation of an average period of 70 years with significant amplitude of 0.3–0.4°C is superimposed on the secular warming trend, which accounts for 40% of the observed warming since the mid-20th century. Tung and Zhou identify this oscillation with the Atlantic Multidecadal Oscillation (AMO), although recent research suggests a more complex multidecadal signal propagating through a network of synchronized climate indices. Tung and Zhou argue that not taking the AMO into account in predictions of future warming under various forcing scenarios may run the risk of over-estimating the warming for the next two to three decades, when the AMO is likely in its down phase.
Consider Hurricane Sandy. Trenberth figures the storm was maybe 5 or 10 percent more powerful as a result of global warming. And sea level is 8 inches higher than it was a century ago. That doesn’t seem that dramatic, but he argues that made a huge and costly difference.
“I reckon that without climate change, we would not have exceeded thresholds that caused the flooding of the subways in Manhattan and the tunnels from Manhattan to New Jersey and to Brooklyn.”
Preliminary damage estimates rank Hurricane Sandy as the 2nd costliest Atlantic hurricane, only behind Hurricane Katrina. When Sandy made landfall, it had been categorized as a post-tropical cyclone with winds equivalent to a Category 1 hurricane. Sandy’s 13 foot storm surge arose from a combination of a very large horizontal extent of the storm plus high tide conditions.
The current elevated hurricane activity in the North Atlantic is associated with the warm phase of the Atlantic Multidecadal Oscillation, which could continue for another decade or two. The recent transition to the cool phase of the Pacific Oscillation is associated with a greater frequency of La Nina events, which are associated with elevated hurricane activity and a preference for Atlantic landfalls (relative to Gulf landfalls).
JC summary: My position on extreme weather events and climate change is much more consistent with IPCC consensus as expressed by the SREX, than is Trenberth’s position. While Trenberth is quick to acknowledge the role of the multi-decadal oscillations in ocean heat storage, he neglects to consider that these same oscillations have a dominant control on the hemispheric weather patterns that influence extreme weather events.
Scientists engaging in policy/politics
From my NPR interview:
“All we can do is be as objective as we can about the evidence and help the politicians evaluate proposed solutions,” she says. If that means doing nothing, “I can’t say myself that that isn’t the best solution.”
And this is where Curry parts company most clearly with her peers. For example, the leading scientific organization for earth scientists, the American Geophysical Union, says in a position statement that climate change “requires urgent action.” It concludes that despite some uncertainties, there’s no scenario where climate change will be inconsequential.
“I don’t know how concerned I should be about it — on what time scale that might happen, whether that’s 100 or 200 years, what societies will be like, what other things are going on with the natural climate,” Curry says. “I just don’t know what the next hundred or 200 years will hold, and whether this will be regarded as an important issue. I just don’t know.”
By now, of course, Curry has strayed far from science and deep into public policy.
“But in terms of telling other people what to do, I don’t have any big answers.”
From Kevin Trenberth’s NPR interview:
Over the decades that he has been working on climate change, the role of scientists has gradually expanded. Prominent scientists like him are trying to reduce the risk of global disruption by pushing society to act. These are frustrating times.
“This is very much in the role of the politicians who are supposed to do what’s in the interests of everybody as a whole,” Trenberth says. “And I’m not so sure many politicians understand their role in this.”
But wading into this policy debate, Trenberth argues that the United States could and should lead the world toward a less dangerous trend.
“If you play the right kind of role, then other countries will follow,” he says.
JC summary: KT and JC obviously disagree substantially on the role of scientists in public debates about policy. KT aligns himself with the consensus in terms of ‘urgent action is needed.’ I stay out of making specific policy recommendations or urging action, saying that i don’t think this the role of scientists and that personally I don’t have any good solutions to this wicked problem. The bizarre thing is that Harris labels me as straying from science and being deep into the politics and in bed with the Republicans.
JC conclusions
I think that Richard Harris missed the real story here: the changing social dynamics of scientists in the climate change debate. What actually differentiates academic scientists in this public debate? It doesn’t seem to be the science.
Virtually all academic climate scientists are within the 97% consensus regarding the infrared emission of the carbon dioxide molecule and the warming effect on the planet. This includes ‘skeptics’ such as Richard Lindzen, Roy Spencer, etc.
The uncertainties surrounding climate sensitivity are such that beliefs as low as 1C and as high as 6C cannot be judged as irrational.
‘Consensus’ scientists are busy investigating the pause cause, using arguments that have been skeptical talking points for several decades.
Few scientists are skeptical of the basic analyses and confidence levels put forward by the IPCC SREX regarding observationally-based assessments of linkages between AGW and extreme weather.
Trenberth has strayed from scientific arguments of the consensus; this seems to be ok if it is more alarming than the consensus.
So . . . what is the differentiator? Why is there such hostility between the two ‘sides’, even though there is little at this point to discriminate the two sides in terms of science? Why have I been thrown off the ‘consensus’ island? Here are my ideas on the differentiators, and they are social (not scientific). I use myself as an example here, since I don’t want to get into talking about or labeling other climate scientists in this regard.
1. Fear and loathing of skeptics, particularly Steve McIntyre (read the Climategate emails for evidence of this). McIntyre is symbolic of attacks against consensus science, and a number of scientists have taken this very personally. My engagement with Steve McIntyre was probably the impetus for my getting tossed off the island, which was very visible with the publication of my post-Climagate essay ‘On the credibility of climate research‘ on McIntyre’s blog.
2. Allegiance to the ‘consensus’ and the social contract between the scientists, institutions and policy makers that has been very beneficial to the field of climate scientists. I have raised concerns about the consensus approach in my uncertainty monster paper and my paper no consensus on consensus. I have also raised concerns about the social contract aspect.
3. The selling of the merchant of doubt and war on science memes, which made uncertainty and doubt dirty words. My uncertainty monster flew directly in the face of this.
4. Expectation of climate scientists to support CO2 mitigation policies. My position is that scientists should stay away from such advocacy unless they understand the policy process and advocate in a responsible way (as per the AAAS workshop guidelines.)
5. Others?
All of this is amplified by the consensus police and denial warriors surrounding the scientific community, including bloggers, the media, NGOs, politicians.
So I have committed 4 major ‘social’ faux pas against the the consensus. Maybe there are others. Tamsin Edwards has arguably scored on three of these; her continued stated loyalty to the consensus seems to have kept her on the island.
Or maybe things are changing? The whole issue of uncertainty seems to be growing in importance. Skeptics are increasingly getting their papers published (including some that have emerged from the skeptical blogosphere). The policy debate has broadened far beyond CO2 mitigation, although climate scientists don’t seem to understand this. Unfortunately, the ostracism of scientists that do not socially support the consensus continues. And the insistence on scientists supporting urgent action on CO2 mitigation continues unabated.
I realize that I am treading into the area of social psychology here, I am throwing these ideas out there in the hopes that some social scientists will pick up on this issue and investigate so that we can better understand the dynamics here, where the tribal differences on a scientific topic are not driven so much by scientific differences but by social issues. I would also like to hear more anecdotes in this regard from other scientists. I am concerned that the social psychology of the allegiance to consensus is getting in the way of moving climate science forward and providing useful information and analyses to support decision making by policy makers.